There are episodes where Sheldon Cooper is being insufferable, and you wish for one of his friends to check his arrogance. The best ones — in 10 seasons, there have been quite a few of them — often involve great Penny and Sheldon moments. “The Locomotion Reverberation” is not such an episode. Sheldon is being all kinds of pain in the tuchus, this time to Howard (one of his favorite targets) and Leonard (ditto), as their long weeks spent whipping up the miniaturized version of their guidance system invention ordered by Air Force colonel Richard Williams (guest star Dean Norris) finally pay off with a model they’re ready to present to the intimidating military man.

In addition to driving Howard and Leonard crazy with his Sheldon-ness — the criticisms, the babbling, the put-downs about Howard being an engineer instead of a “real” scientist — Sheldon’s also been noodling with some calculations that lead him to the conclusion the device can be made even smaller. His friends aren’t interested in such improvements, however, preferring to pass on doing yet more work, and instead pass along what they already have in hand.

“Where would we be if poodle breeders had that attitude?” Sheldon responds to their nonchalance about the possibility of further miniaturization. “We would have the standard and miniature poodle, but no toy or teacup.”

They are undeterred by his poodle logic, however, and when Sheldon returns from yet another potty break — Howard’s been secretly refilling his water cup to facilitate any excuse to keep Sheldon out of their shared workspace as much as possible — Leonard reveals he’s been hoarding a sure-fire way to keep Sheldon out of their hair. Several years ago, he purchased a $4,000 gift certificate for Sheldon to attend an interactive train conductor experience in Nevada. He’s been saving it for an occasion when Sheldon is at his most annoying, and the prospect of being needled into spending more time at work on the guidance system has sparked him to present superfan of all things train-related to Sheldon. The gift is well received, of course, and even prompts Sheldon to issue something only one other gift has elicited from him: a hug (which he also gave to Penny in season two’s “The Bath Item Gift Hypothesis,” when she presented him with a napkin used by Leonard Nimoy during his visit to the Cheesecake Factory).

Leonard smugly thinks he has rid himself and Howard of the only thing standing between them and making the final hand off to Col. Williams, but — bazinga! — he wasn’t clever enough to take care of one very important detail: erasing Sheldon’s whiteboard. When Williams, an engineer himself, comes to the office, he glances at Sheldon’s work and realizes it means the guidance system can be even smaller. Leonard and Howard try to talk him out of it, but he’s clear this new approach is what he wants, and suggests they have “the kid with the two shirts” do it, which may be the single best description of Sheldon that’s been deployed throughout the series.

“The kid with the two shirts screwed us again,” Howard says, and you can’t feel sorry for him and Leonard, because they were just trying to get out of doing more work, while Sheldon was actually trying to improve something and hand in the best guidance system possible. Since Col. Williams — again, the very intimidating Col. Williams — insists on the even-smaller makeover, Howard and Leonard try to trick Sheldon again. They can’t understand how to continue the calculations he started, and Sheldon is so preoccupied with preparing for his trip to train camp that he’s considering quitting science to become a train engineer. So Leonard scribbles some symbols under Sheldon’s work, including a squiggle that looks like Charlie Brown’s hair, and assumes Sheldon will be compelled to complete the equation correctly, because … he’s Sheldon.

Sheldon does indeed finish what Leonard started … by drawing the rest of Charlie Brown’s face.

Busted, but still in desperate need of help, Howard offers to teach Sheldon how to work on mechanical projects, like the guidance system, so he can actually help them retool it for Williams (and he’ll have the skills to be able to fix any model train), if he’ll agree to finish up the calculations for the re-miniaturization.

My final calculation: (Leonard and Howard trying to use Sheldon’s love of trains and his sincere desire to always do his best work against him to get out of doing more work themselves) + (Sheldon getting a $4,000 experience and new skills that will allow him to enjoy his favorite hobby even more) = Sheldon 2, Leonard and Howard 0.

Elsewhere, motherhood is stressing Bernadette out big time, so Penny and Amy offer to take her out for an evening of fun that involves no babies crying and no milk being pumped. Amy suggests a joint concert between the Early Music Society of Pasadena and the San Diego Renaissance Choir, which is nixed for a night of club dancing instead, but they arrive at the club only to find it’s been replaced by a bookstore. Bernie’s dream of a pleasant, stress-free night out quickly becomes as unlikely as there being a city where bookstores are replacing dance clubs (if this city does exist, please alert the media, because I want to go to there), as repeated phone calls from babysitters Raj and Stuart only remind Bernie of her new responsibilities, and impress upon Amy and Penny that while the Wolowitzes lives are moving forward at a pretty good pace, both the Hofstadter marriage and Amy’s I’m-not-even-engaged-yet relationship with Sheldon feel stale.

Here’s hoping that isn’t going to become a thing, because 1) Penny and Leonard are not stable enough as a couple for Penny to start thinking it’s baby time, and 2) yes, Sheldon and Amy are the one couple who should be at least engaged by now, but it’s not like they haven’t been moving their relationship forward. They moved in together earlier this season. Also, Amy’s assertion that Sheldon never even thinks about marriage … so not true. She knows, in fact, that he has his Meemaw’s wedding ring in his possession, ready to be deployed as an engagement ring.

As for the Raj and Stuart babysitters club storyline, it gets no stars. There is so much potential with both those characters and both those actors. Why does the audience see that more than the TBBT writer’s room?

THEOR-EMS:

• “Wow … he finally used it? What did you do?” Amy, reacting to Sheldon’s news about Leonard’s ulterior motive gift, thus revealing that she already knew about it.